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Handicap calculator
Paste your last 20 Score Differentials - the per-round figures your club's app or England Golf record already shows - and this works out your Handicap Index exactly as World Handicap System Rule 5.2b does: the lowest 8, averaged, rounded to the nearest tenth.
Based on Rule 5.2b of the R&A Rules of Handicapping.
This is the uncapped Rule 5.2b calculation. Your club's system may apply a cap against your Low Handicap Index (Rule 5.8), and the fewer-than-20-scores table (Rule 5.2a) is not covered here.
What a Score Differential already carries
The differential is the adjusted figure, not your gross score: it is your adjusted gross score measured against the Course Rating and Slope Rating of the tees you played, with the day's playing-conditions adjustment included. That is why this tool asks for differentials rather than scores - Rule 2 builds the course into the number, and the conversion from a card you kept needs the PCC figure for that day, which only the system knows. Your club's app shows the differential for every accepted round.
Why the lowest 8 of 20
Rule 5.2b averages the lowest 8 of your most recent 20 differentials and rounds to the nearest tenth. Averaging only your best rounds is what makes the index measure demonstrated ability rather than your worst Saturdays; taking them from the last 20 is what makes it move with your current game. A single disaster barely registers; a genuine run of form does.
What this tool does not do
Three honest limits. It does not apply Rule 5.8's caps, because they hinge on your Low Handicap Index, which your club's record tracks - so a long-standing low index may see the official number sit above this one. It does not cover records shorter than 20 scores, because Rule 5.2a's table is published by the R&A and we will not reproduce it from memory. And it does not convert raw scores into differentials, because that needs each round's Course Rating, Slope Rating and playing-conditions adjustment.
When the number comes back, what counts as a good handicap puts it in context, and how a handicap is calculated walks the whole mechanism.
The calculation is Rule 5.2b of the Rules of Handicapping, read 2026-09-08: average the lowest 8 of your most recent 20 Score Differentials and round to the nearest tenth. That is everything this tool does, so the result is the uncapped index your record's arithmetic produces.
It deliberately leaves out what the R&A does not publish as text or what only your club's system knows: the fewer-than-20-scores table, the Rule 5.8 caps, and the conversion from raw cards into differentials.
Written by Craig Fearn, The Golf Gift Co.